Genetic Engineering

1. Genetic Engineering

2. Genetic Variation • You can compare dogs of every breed imaginable! • There is an enormous range of characteristics that are the result of genetic variation. • The differences among breeds of dogs are so great that someone might think that many of these breeds are different species. • They're not, of course, but where did such differences come from?

3. Selective Breeding • The answer, of course, is that we did it. • Humans have kept and bred dogs for thousands of years, always looking to produce animals that might be better hunters, better retrievers, or better companions. • By selective breeding, allowing only those animals with desired characteristics to produce the next generation, humans have produced many different breeds of dogs.

4. Selective Breeding • The ancestor of modern corn had tiny kernels, each protected by a tough husk. • Domestication of maize, which began thousands of years ago, selected for large sheathed cobs containing large kernels without husks.

5. Hybridization • Hybridization - Breeding technique that involves crossing dissimilar individuals to bring together the best traits of both organisms. • Hybrids, the individuals produced by such crosses, are often hardier than either of the parents.

6. Zeedonk - Zebra and Donkey Liger – Lion and Tiger Jaglion- Jaguar and Lion

7. Inbreeding • To maintain the desired characteristics of a line of organisms, breeders often use a technique known as inbreeding. • Inbreeding is the continued breeding of individuals with similar characteristics. • The many breeds of dogs—from beagles to poodles—are maintained by inbreeding. Inbreeding helps to ensure that the characteristics that make each breed unique will be preserved.

8. Risks of Inbreeding • Although inbreeding is useful in retaining a certain set of characteristics, it does have its risks. • Most of the members of a breed are genetically similar. • Because of this, there is always a chance that a cross between two individuals will bring together two recessive alleles for a genetic defect. • Serious problems in many breeds of dogs, including blindness and joint deformities in German shepherds and golden retrievers, have resulted from excessive inbreeding.

9. Increasing Variation • Selective breeding would be nearly impossible without the wide variation that is found in natural populations. • Breeders can increase the genetic variation in a population by inducing mutations, which are the ultimate source of genetic variability.

10. Increasing Variation • As you may recall, mutations are inheritable changes in DNA. • Mutations occur spontaneously, but breeders can increase the mutation rate by using radiation and chemicals. • Many mutations are harmful to the organism.

11. Polyploidy • Polyploidy is usually fatal in animals. • However, for reasons that are not clear, plants are much better at tolerating extra sets of chromosomes. • Polyploidy may instantly produce new species of plants that are often larger and stronger than their diploid relatives.

12. Genetic Engineering • Genetic Engineering - Process of making changes in the DNA code of living organisms. • Includes: • DNA Extraction • The cells are opened and the DNA is separated from the other cell parts. • Cutting DNA • Separating DNA

13. Genetic Engineering: Cutting DNA • DNA molecules from most organisms are much too large to be analyzed, so biologists cut them precisely into smaller fragments using restriction enzymes.

14. Genetic Engineering: Separating DNA • Gel electrophoresis - Procedure used to separate and analyze DNA fragments by placing a mixture of DNA fragments at one end of a porous gel and applying an electrical voltage to the gel • When the power is turned on, DNA molecules, which are negatively charged, move toward the positive end of the gel. • The smaller the DNA fragment, the faster and farther it moves.

15. Gel Electrophoresis • Uses of gel electrophoresis: • Compare the genomes, or gene composition, of different organisms or different individuals. • Locate and identify one particular gene out of the tens of thousands of genes in an individual's genome.

17. Recombinant DNA • Recombinant DNA - DNA produced by combining DNA from different sources. • Can join “synthetic” sequences to “natural” ones using enzymes that splice DNA together. • Is possible to take a gene from one organism and attach it to the DNA of another organism by using enzymes.

18. Transformation • During transformation, a cell takes in DNA from outside the cell. This external DNA becomes a component of the cell's DNA.

19. Bacteria Transformation • Plasmid - Circular DNA molecule found in bacteria. • Plasmids are found naturally in some bacteria and are useful for DNA transfer. Why?

20. Bacteria Transformation

21. Is it Possible to Transfer Whole Genes From One Organism to Another? • In 1986, American researcher Steven Howell transferred the gene for luciferase into tobacco plant cells. • Luciferase is an enzyme that allows fireflies to glow. • The plants glowed in the dark!

22. Transgenic Organisms • Transgenic - Term used to refer to an organism that contains genes from other organisms. • Transgenic Bacteria • Reproduce rapidly and are easy to grow. • Bacteria transformed with the genes for human proteins now produce these important compounds cheaply and in great abundance.

23. Transgenic Organisms • Transgenic Animals • Used to study genes and to improve the food supply. • Mice have been produced with human genes that make their immune systems act similarly to those of humans. • Some transgenic livestock now have extra copies of growth hormone genes.

24. Transgenic Organisms • Transgenic Plants • Are now an important part of our food supply. • In the year 2000, 52% of the soybeans and 25% of the corn grown in the US were transgenic, or genetically modified (GM). • Some GM plants contain genes that produce a natural insecticide. • Other crop plants have genes that enable them to resist weed-killing chemicals.

25. Cloning • Clone - Member of a population of genetically identical organisms produced from a single cell. • Cloned colonies of bacteria and other microorganisms are easy to grow, but this is not always true of multicellular organisms, especially animals.

26. Cloning Animals • In 1997, Scottish scientist Ian Wilmut stunned biologists by announcing that he had cloned a sheep, which he later named Dolly. • How did he do it? • The nucleus of an egg cell is removed. • The cell is fused with a cell taken from another adult. • The fused cell begins to divide and the embryo is then placed in the reproductive system of a foster mother, where it develops normally.

27. Cloning • Cloned cows, pigs, mice, and other mammals have been produced by similar techniques. • Researchers hope that cloning will enable them to make copies of transgenic animals and even help save endangered species. • On the other hand, the technology is controversial for many reasons, including studies suggesting that cloned animals may suffer from a number of genetic defects and health problems. • The use of cloning technology on humans, while scientifically possible, raises serious ethical and moral issues that have caused many people to oppose such work. As techniques improve, these important issues will become even more pressing.

28. Clone Member of a population of genetically identical organisms produced from a single cell. CC with surrogate mom Genetic mom CC = Copy Cat (the clone) CC gives birth to 3 healthy kittens